Trust in many areas of computing has been and will continue to be a desirable feature due to the continual attacks on hardware and software systems to gain access to user information, financial information, system control, and any other goal of the unauthorized attack.
Given that in the computing world, rarely are the parties to a transaction in direct face-to-face contact, it then becomes important to establish some level of trust in the other party. Existing technologies include the use of public and private keys, certificate authorities, and so on.
There are different levels and types of trust. The expectation of a behavior does not apply to all things equally as expectations of an individual depend on the identity of the individual and the role that the individual is being expected to serve. For example, one party might trust a banker with to oversee a bank and savings but not children; while the party might trust a relative to look after the children, but not the bank account.
When performing online banking, it is especially important to know that the transaction is with a bank computer rather than the computer of a thief. If it is determined the connection is with a thief, the thief will not indicate they are a thief; thus, the object is to ensure that the transaction is being handled by the bank's computer.